JP2005174594A - Color display using electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new color display system different from the color display system provided conventionally. <P>SOLUTION: The color display forms one pixel from a plurality of sub-pixels and is constructed by arranging a plurality of pixels. Then, each sub-pixel is provided with (a) organic EL elements 1R, 1G, 1B which at least emit light of a wavelength that the sub-pixel emits, and (b) two-dimensional photonics crystal layers 2R, 2G, 2B for the wavelength emitted by the sub-pixel which are provided on the light extraction side than the organic EL elements 1R, 1G, 1B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, a color using an electroluminescent element such as an organic electroluminescent element (hereinafter appropriately referred to as “organic EL element”) or an inorganic electroluminescent element (hereinafter appropriately referred to as “inorganic EL element”). More particularly, the present invention relates to a color display using a two-dimensional photonic crystal technique.

2. Description of the Related Art Conventionally, color displays using electroluminescent elements have attracted attention, and various conventional techniques have been proposed. For example,
(A) For each sub-pixel constituting each pixel, an organic EL element that emits red (R), an organic EL element that emits blue (B), and an organic EL element that emits green (G) are separately formed (evaporation). Sort, paint separately), RGB independent formation method using mask vapor deposition method and inkjet paint separation method,
(B) Using an organic EL element that emits white light in each of RGB sub-pixels using a color filter or the like, and dimming light that does not need to be emitted. For example, the R sub-pixel has a G wavelength band . Color filter method to cut light and light in the B wavelength band ,
(C) An energy conversion method such as a fluorescence conversion method for expressing RGB by converting high energy light such as blue or ultraviolet light into a low energy color such as yellow or red,
(For example, refer nonpatent literature 1).
“Organic EL materials and displays”, p. 331, CMC Co., Ltd., supervised by Keiji Koji, February 28, 2001 Supervised by Seizo Miyata, “Organic EL devices and their industrialization fronts”, NTS Co., Ltd., issued on November 30, 1998, p. 46-47, FIG. “Control of Light Field by Photonic Crystal”, Surface Science Vol. 11, pp 702-709, 2001) "Characteristic evaluation of photonic crystal organic EL device", Proceedings of the 64th JSAP academic lecture, p938 “Preparation of organic semiconductor photonic crystals and their optical properties”, Proceedings of the 64th Japan Society of Applied Physics, p938

  The inventor of the present application proposes a new color display system using electroluminescent elements, which is different from the conventionally proposed color display system using electroluminescent elements.

The color display using the electroluminescent element proposed by the present inventor is as follows.
The first color display is composed of a plurality of sub-pixels, each pixel being arranged. Each subpixel includes (a) an electroluminescence element that emits at least light having a wavelength emitted from the subpixel, and (b) a wavelength-providing element provided on the light extraction side of the electroluminescence element. And a two-dimensional photonic crystal layer.

  The second color display is configured by forming one pixel by a plurality of sub-pixels and arranging a plurality of pixels. Each subpixel is provided with (c) an electroluminescent element and (d) a two-dimensional photonic crystal layer for a wavelength emitted from the subpixel, which is provided on the light extraction side of the electroluminescent element. . Further, (e) the electroluminescent elements of each subpixel are elements that emit light having a wavelength emitted from all the subpixels.

In the first to second color displays, the electroluminescent elements in each subpixel may have substantially the same layer configuration.
Further, the electroluminescent element may be an organic electroluminescent element.

  In the present specification, “transparent” means that the light emitted from the organic layer has transparency to light having at least one wavelength, or light having a wavelength within a certain region including this wavelength. Unless otherwise specified, it preferably has a transmittance of 50% or more, desirably 70% or more. The term “transmitting light” is also used appropriately in the same meaning as “transparent”.

  In the present specification, the “two-dimensional photonic crystal layer” means a layer having the above-described two-dimensional photonic crystal structure, and in the layered transparent member (first dielectric), A member in which a large number of portions (second dielectrics) having a refractive index different from that of the member are periodically introduced in a direction perpendicular to the surface, that is, in a thickness direction.

The substantially identical layer structure means that the layer structure of each electroluminescent element is substantially the same. For example, each element is composed of the same number of layers, and each layer has substantially the same function in order from the anode side. Configuration. More specifically, this is the case where functions such as a hole transport function and a light emitting function are the same. In this case, the concept of “layer” can be replaced with the concept of “region”. For example, at the position where the hole injection transport layer (hole injection transport region) is provided in one element, in the other element, when the hole injection layer and the hole transport layer are sequentially laminated, It can be said that “substantially the same layer structure”.
In addition, the corresponding layers in each element need only have substantially the same function, and the film thickness, the constituent material, the film forming method, and the like may be the same or different.
The materials contained in the corresponding layers may be approximately the same. Specifically, the substantially same material is a material generally referred to as being similar, such as a material belonging to the same derivative or a material having a similar three-dimensional structure.

  As described above, according to the present invention, a color display using an electroluminescent element having a novel configuration can be provided.

Hereinafter, a color display using an electroluminescent element according to an embodiment of the present invention will be described using a color display using an organic EL element, but the electroluminescent element is changed to another element such as an inorganic EL element. Of course it is possible.
In the following description, an organic EL element having a bottom emission structure will be described, but it is naturally possible to adopt a top emission structure or to change to another known light extraction structure.

In each drawing, the same reference numerals are assigned to the same or similar components. Each figure is a diagram (schematic diagram, enlarged view of main part, etc.) for explaining the structure of an organic EL device or the like, and one or more components are extremely different from an actual organic EL device or the like. Shown in different dimensions.
First, a first color display according to the present embodiment will be described with reference to FIGS.

《First color display》
One pixel is constituted by a plurality of sub-pixels, and a plurality of pixels are arranged. Each subpixel includes (a) an organic EL element that emits at least light having a wavelength emitted from the subpixel, and (b) a wavelength-provided wavelength that is provided on the light extraction side of the organic EL element. And a two-dimensional photonic crystal layer.

As shown in FIG. 1, one pixel of the first color display is composed of RGB sub-pixels. Each RGB subpixel includes an organic EL element 1R that emits red, an organic EL element 1G that emits green, and an organic EL element 1B that emits blue, and emits light in the wavelength bands of at least red, green, and blue, respectively. Each organic EL element 1R, 1G, 1B is formed on one surface (light incident surface 31) of the same transparent substrate 3, respectively.

  On the other surface (light emitting surface 32) of the transparent substrate 3, two-dimensionally transmits a color corresponding to a color emitted from each subpixel to the outside at a position corresponding to each organic EL element 1R, 1G, 1B. Each of the photonic crystal layers 2 is provided. That is, the two-dimensional photonic crystal layer 2 </ b> R that transmits light of the red wavelength is provided in the red sub-pixel that includes the organic EL element 1 </ b> R. A two-dimensional photonic crystal layer 2G that transmits light having a green wavelength is provided in a green sub-pixel including the organic EL element 1G. A sub-pixel emitting blue light provided with the organic EL element 1B is provided with a two-dimensional photonic crystal layer 2B that transmits light of a blue wavelength.

As described above, in the first display, the two-dimensional photonic crystal layer 2 for the wavelength (or wavelength band ) emitted from the sub-pixel is provided in each sub-pixel on the light extraction side from the organic EL element 1. Therefore, so-called sharp light is emitted in which the intensity of the wavelength (or wavelength band ) emitted from each sub-pixel is extremely higher than the intensity of the adjacent wavelength (or wavelength band ).

  Further, in FIG. 1, the front luminance is higher than that of a display in which the two-dimensional photonic crystal layer is not provided. In other words, even when the amount of light emitted from the organic EL element 1 is small, it is possible to obtain sufficient luminance as a display.

By these actions, for example, the following effects can be obtained.
The organic EL element 1 that cannot emit a sufficient amount of light as a display can be adopted.
Since each subpixel is provided with the two-dimensional photonic crystal layer 2 for the wavelength emitted from each subpixel, even if the amount of light emitted from the organic EL element 1 is small, the two-dimensional photonic crystal is used. This is because it is strengthened by layer 2.

・ Power consumption can be reduced.
Since the two-dimensional photonic crystal layer 2 is provided, it is possible to obtain sufficient luminance as a display even if the amount of light emitted from the organic EL element 1 is reduced. This is because, in order to obtain an amount of light equivalent to that of a display in which the photonic crystal layer 2 is not provided, the amount of current flowing through the organic EL element 1 can be reduced. This is an effect of the EL element 1 based on the general rule that “the greater the amount of current flowing through the element, the greater the amount of emitted light” (for example, Non-Patent Document 2). See).

In FIG. 1, the configuration in which the transparent substrate 3 is sandwiched between the organic EL element 1 and the two-dimensional photonic crystal layer 2 is used. As described above, the two-dimensional photonic crystal layer 2 is composed of the organic EL element. It may be present on the light extraction side rather than 1. Therefore, the two-dimensional photonic crystal layer 2 may be provided adjacent to the surface on the light extraction side of the organic EL element 1. That is, in FIG. 1, it may be provided between the transparent substrate 3 and the organic EL element 1. In FIG. 1, a top emission structure in which the organic EL element 1 is provided between the two-dimensional photonic crystal layer 2 and the transparent substrate (or simply substrate) 3 may be used.
Hereinafter, the configuration and manufacturing method of the two-dimensional photonic crystal layer 2, the organic EL element 1, and the substrate 3 will be described in detail, and then a method of driving as a display will be described.

<Two-dimensional photonic crystal layer 2>
A photonic crystal is a substance / element device that can freely control light having a periodic structure with a length of about the wavelength of light or electromagnetic waves. Specifically, a photonic crystal has a periodic structure with a length of about the wavelength of light, in which there is a photonic band-gap that does not relax the presence of light in a certain wavelength range. appear. The origin of this photonic pandagap can be explained in the same way as the origin of the bandgap, forbidden band for electrons in a solid crystal, ie, the bandgap where the presence of electrons in a specific energy range is not allowed.

When atoms are regularly arranged in a certain period in a solid crystal, the band gap for electrons appears because the wavelength when the electrons are viewed as waves is just as large as the atomic spacing. Bragg reflection is received by the periodic potential, and a state without energy is formed.
In the same way, when transmitting through a structure with a periodic refractive index (dielectric constant) distribution of the same length as the wavelength of light, the photonic band gap is prohibited from propagating light in a certain wavelength band. Is formed. This periodic structure may be one-dimensional, two-dimensional, or three-dimensional.

In addition, when a defect is introduced into a photonic crystal having a complete periodic structure, the band edge has a tail in the photonic band gap, and a defect level (localized level) appears in the band. By using this defect level, it is possible to enhance the light emission characteristics of the light emitting substance. Further, the group velocity of light becomes extremely small at the band edge, and as a result, it is possible to enhance the light emission characteristics of the entire device (see, for example, Non-Patent Documents 3 to 5).
Hereinafter, the configuration of the two-dimensional photonic crystal layer 2 in FIG. 2 will be specifically described.

  As shown in FIG. 2A, the two-dimensional photonic crystal layer 2 is a layered (plate-shaped) material (first dielectric) 21 that is transparent with respect to the wavelength of light emitted from the organic EL element 1. A portion (second dielectric) 22 that is transparent to the light and has a refractive index (dielectric constant) different from that of the material, in which the thickness direction, that is, the normal direction of the layer is the longitudinal direction. Are layers arranged periodically. In FIG. 2A, the second dielectric 22 in the first dielectric 21 is also shown by a solid line for the sake of explanation.

  As described above, the two-dimensional photonic crystal layer 2 is strengthened or sharpened with respect to one wavelength of light emitted from the organic EL element 1 or a wavelength within a predetermined range centered on the wavelength. What is necessary is just to take the structure to do. That is, the refractive indexes of the first dielectric material 21 and the second dielectric material 22 and the arrangement method (periodicity) of the second dielectric material are calculated using a known photonic crystal technique. It may be produced accordingly. As a manufacturing method, a known photonic crystal manufacturing method can be employed. For example, the photonic crystal can be manufactured using photolithography or can be manufactured by electron beam drawing.

  Examples of the periodic structure of the second dielectric include a square arrangement as shown in FIG. 2B and a triangular lattice arrangement as shown in FIG.

The material constituting the first dielectric 21 and the second dielectric 22 may be any refractive index different from each other. For example, any glass material, semiconductor material, oxide material, organic material, or the like is applicable. .
In addition, gas or vacuum can be regarded as one material. That is, the two-dimensional photonic crystal layer 2 may be manufactured by making a hole in the first dielectric 21 and filling the hole with a gas such as air or nitrogen, or by making a vacuum. When such a structure is adopted, the gas sealed in the hole is preferably a gas that does not deteriorate or hardly deteriorate the organic layer 3 or the like. For example, nitrogen or a rare gas is sealed. Is preferred.
Next, the organic EL element 1 will be described with reference to FIG.

<Organic EL element 1>
As shown in FIG. 3, the organic EL element 1 is a layer in which an organic layer 12 containing an organic light emitting material is provided between a transparent electrode 10 and a back electrode 12, and light is emitted when voltage is applied to both electrodes. In other words, a known layer structure and a known material layer in a known organic EL element may be used, and the layer can be manufactured by a known manufacturing method. Note that the emission wavelength is designed to be light having a wavelength that is transmitted through at least the two-dimensional photonic crystal layer 2 for each subpixel for the reason described above. The transparent electrode 10 is provided on the light extraction side with respect to the organic layer 11.

(Organic layer 11)
For example, the organic layer 11 may have the following layer structure.
・ (Anode) / Hole injection layer / Hole transport layer / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Hole injection layer / Hole transport layer / Light emitting layer / Electron injection transport layer / (Cathode)
・ (Anode) / Hole injection / transport layer / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Hole injection / transport layer / Light emitting layer / Electron injection / transport layer / (Cathode)
・ (Anode) / Hole transport layer / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Hole transport layer / Light emitting layer / Electron injection transport layer / (Cathode)
・ (Anode) / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Light emitting layer / Electron injection / transport layer / (Cathode)
・ (Anode) / Light emitting layer / (Cathode)

That is, the following functions required for the organic layer 11 may be realized by a single layer or a plurality of layers.
-Electron injection function Function to inject electrons from the electrode (cathode). Electron injection.
・ Hole injection function Function to inject holes from the electrode (anode). Hole injection property.
・ Carrier transport function Function to transport at least one of electrons and holes. Carrier transportability.
The function of transporting electrons is called an electron transport function (electron transportability), and the function of transporting holes is called a hole transport function (hole transportability).
-Luminescence function A function that emits light when returning to the ground state by recombining injected and transported electrons and carriers to generate excitons (in an excited state).

Of course, other layers constituting a known organic layer may be provided.
In the following, an example in which the organic layer is composed of a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer will be described, and the case where other structures are employed will be described.

  In addition, it is preferable that the organic layer 11 (and also the organic EL element 1) in each subpixel has the same configuration except for the layer contained in the light emitting layer that is a layer contributing to light emission. This is because it is possible to manufacture each layer (and also the electrode) other than the light emitting layer and each subpixel at the same time.

[Hole injection transport layer]
The hole injection / transport layer is a layer provided between the anode and the light emitting layer, and is a layer in which holes are injected from the anode and the injected holes are transported to the light emitting layer. Generally, the ionization potential of the hole injection transport layer is set to be between the work function of the anode and the ionization potential of the light emitting layer, and is usually set to 5.0 eV to 5.5 eV.
The organic EL element shown in FIG. 1 has the following properties by including a hole injecting and transporting layer.
・ Low drive voltage.
-Since the injection of holes from the anode to the light emitting layer is stabilized, the life of the device is extended.
-Since the adhesion between the cathode 10 and the light emitting layer is increased, the uniformity of the light emitting surface is increased.
・ Element defects can be reduced by covering anode protrusions.

  Further, when the hole injecting and transporting layer is provided closer to the light extraction side than the light emitting layer, it is formed transparent to the extracted light. A material that is transparent to the light when the film is thinned is appropriately selected from materials that can form the hole injecting and transporting layer. Generally, the transmittance for the extracted light is set to be larger than 10%. Be done

  The material for forming the hole injecting and transporting layer is not particularly limited as long as it imparts the above properties to the hole injecting and transporting layer, and known materials that can be used as the hole injecting material for the photoconductive material, Any material can be selected and used from known materials used for the hole injection transport layer of the organic EL element.

  For example, phthalocyanine derivatives, triazole derivatives, triarylmethane derivatives, triarylamine derivatives, oxazole derivatives, oxadiazole derivatives, stilbene derivatives, pyrazoline derivatives, pyrazolone derivatives, polysilane derivatives, imidazole derivatives, phenylenediamine derivatives, amino-substituted chalcone derivatives, Styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, aniline copolymers, porphyrin compounds, polyarylalkane derivatives, polyphenylene vinylene and its derivatives, polythiophene and its derivatives, poly-N-vinylcarbazole derivatives, thiophene oligomers, etc. Conductive polymer oligomer, phthalocyanine derivative, carbazole derivative, quinacridone compound, aromatic Tertiary amine compounds, and the like styrylamine compound.

  Triarylamine derivatives include, for example, triphenylamine dimer to tetramer, 4,4′-bis [N-phenyl-N- (4 ″ -methylphenyl) amino] biphenyl, 4,4′- Bis [N-phenyl-N- (3 ″ -methylphenyl) amino] biphenyl, 4,4′-bis [N-phenyl-N- (3 ″ -methoxyphenyl) amino] biphenyl, 4,4′-bis [ N-phenyl-N- (1 ″ -naphthyl) amino] biphenyl, 3,3′-dimethyl-4,4′-bis [N-phenyl-N- (3 ″ -methylphenyl) amino] biphenyl, 1,1 -Bis [4 '-[N, N-di (4 "-methylphenyl) amino] phenyl] cyclohexane, 9,10-bis [N- (4'-methylphenyl) -N- (4" -n-butyl) Phenyl) amino] phena Tren, 3,8-bis (N, N-diphenylamino) -6-phenylphenanthridine, 4-methyl-N, N-bis [4 ", 4 '"-bis [N', N "- Di (4-methylphenyl) amino] biphenyl-4-yl] aniline, N, N ″ -bis [4- (diphenylamino) phenyl] -N, N′-diphenyl-1,3-diaminobenzene, N, N'-bis [4- (diphenylamino) phenyl] -N, N'-diphenyl-1,4-diaminobenzene, 5,5 "-bis [4- (bis [4-methylphenyl] amino) phenyl]- 2,2 ′: 5 ′, 2 ″ -terthiophene, 1,3,5-tris (diphenylamino) benzene, 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine, 4,4 ′, 4 "-Tris [N- (3 '' ' Methylphenyl) -N-phenylamino] triphenylamine, 4,4 ′, 4 ″ -tris [N, N-bis (4 ′ ″-tert-butylbiphenyl-4 ″ ″-yl) amino] triphenylamine 1,3,5-tris [N- (4′-diphenylaminophenyl) -N-phenylamino] benzene.

  Examples of porphyrin compounds include porphine, 1,10,15,20-tetraphenyl-21H, 23H-porphine copper (II), 1,10,15,20-tetraphenyl-21H, 23H-porphine zinc (II). 5,10,15,20-tetrakis (pentafluorophenyl) -21H, 23H-porphine and the like.

  Examples of phthalocyanine derivatives include silicon phthalocyanine oxide, aluminum phthalocyanine chloride, phthalocyanine (metal free), dilithium phthalocyanine, copper tetramethylphthalocyanine, copper phthalocyanine, chromium phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium phthalocyanine oxide, magnesium phthalocyanine, copper Examples include octamethyl phthalocyanine.

  Examples of the aromatic tertiary amine compound and the styrylamine compound include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl, N, N′-diphenyl-N, N′-bis. -(3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine, 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1-bis (4- Di-p-tolylaminophenyl) cyclohexane, N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminophenyl, 1,1-bis (4-di-p-tolylaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N′-diphenyl-N, N′-di ( 4-me Xylphenyl) -4,4′-diaminobiphenyl, N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl ether, 4,4′-bis (diphenylamino) quadriphenyl, N, N , N-tri (p-tolyl) amine, 4- (di-p-tolylamino) -4 ′-[4 (di-p-tolylamino) styryl] stilbene, 4-N, N-diphenylamino- (2-diphenyl) Vinyl) benzene, 3-methoxy-4′-N, N-diphenylaminostilbenzene, N-phenylcarbazole and the like. Aromatic dimethylidin compounds can also be used as the material for the hole injecting and transporting layer 310.

Examples of the carbazole derivative include carbazole biphenyl and N-methyl-
N-phenylhydrazone-3-methylidene-9-ethylcarbazole, polyvinylcarbazole, Nisopropylcarbazole, Nphenylcarbazole and the like can be mentioned.

  The hole injecting and transporting layer may be formed from one of the materials as described above, or may be formed by mixing a plurality of materials. Moreover, the multilayer structure which consists of several layers of the same composition or a different composition may be sufficient.

The hole injecting and transporting layer may be formed on the anode by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.
Although the film thickness depends on the material to be selected, it is usually 5 nm to 5 μm.

[Light emitting layer]
The light-emitting layer is mainly composed of an organic material, and holes and electrons are injected from the anode side and the cathode side, respectively, and transports at least one of the holes and electrons to recombine them to create excitons (excited state). It is a layer that emits light when the exciton returns to the ground state.

Therefore, the material for forming the light emitting layer (organic material) only needs to have the following functions.
-A hole injection function capable of injecting holes from the hole injection transport layer (or anode).
An electron injection function that can inject electrons from the electron injection transport layer.
A transport function that moves at least one of injected holes and electrons by the force of an electric field.
A function that recombines electrons and holes to generate an excited state (exciton).
A function for generating light when returning from the excited state to the ground state.

Typical examples of the material having the above functions include Alq3 and Be-benzoquinolinol (BeBq2).
The following materials can also be used.

2,5-bis (5,7-di-t-pentyl-2-benzoxazolyl) -1,3,4-thiadiazole, 4,4′-bis (5,7-benzyl-2-benzoxazolyl L) Stilbene, 4,4′-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl] stilbene, 2,5-bis (5,7-di-t-) Benzyl-2-benzoxazolyl) thiophine, 2,5-bis ([5-α, α-dimethylbenzyl] -2-benzoxazolyl) thiophene, 2,5-bis [5,7-di- ( 2-methyl-2-butyl) -2-benzoxazolyl] -3,4-diphenylthiophene, 2,5-bis (5-methyl-2-benzoxazolyl) thiophene, 4,4′-bis ( 2-Benzoxazolyl) biphenyl, 5-methyl-2- [2- [4 Benzoxazoles such as-(5-methyl-2-benzoxazolyl) phenyl] vinyl] benzoxazolyl, 2- [2- (4-chlorophenyl) vinyl] naphtho [1,2-d] oxazole; 2 , 2 ′-(p-phenylenedivinylene) -bisbenzothiazole and the like; 2- [2- [4- (2-benzimidazolyl) phenyl] vinyl] benzimidazole, 2- [2- (4-carboxyl) Phenyl) vinyl] benzimidazole and other fluorescent whitening agents,

Bis (8-quinolinol) magnesium, bis (benzo-8-quinolinol) zinc, bis (2-methyl-8-quinolinolate) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum 8-quinolinol lithium, tris (5-chloro-8-quinolinol) gallium, bis (5-chloro-8-quinolinol) calcium, poly [zinc-bis (8-hydroxy-5-quinolinyl) methane] Hydroxyquinoline-based metal complexes; metal chelated oxinoid compounds such as dilithium ependridione; 1,4-bis (2-methylstyryl) benzene, 1,4- (3-methylstyryl) benzene, 1,4-bis (4-methylstyryl) benzene, distyrylbenzene, 1,4- Styrylbenzene compounds such as s (2-ethylstyryl) benzene, 1,4-bis (3-ethylstyryl) benzene, 1,4-bis (2-methylstyryl) 2-methylbenzene; 2,5-bis ( 4-methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) pyrazine, 2,5-bis [2- (1-naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, Distil pyrazine derivatives such as 2,5-bis [2- (4-biphenyl) vinyl] pyrazine, 2,5-bis [2- (1-pyrenyl) vinyl] pyrazine; naphthalimide derivatives; perylene derivatives; oxadiazole Derivatives; aldazine derivatives; cyclopentadiene derivatives; styrylamine derivatives; coumarin derivatives; aromatic dimethylidin derivatives; anthracene Salicylate; pyrene; coronene and,

Fac-tris (2-phenylpyridine) iridium, bis (2-phenylpyridinato-N, C2 ′) iridium (acetylacetonate), 6-di (fluorophenyl) -pyridinate-N, C2 ′) iridium (acetyl) Acetonato), iridium (III) bis [4,6-di (fluorophenyl) -pyridinate-N, C2 ′] picolinate, platinum (II) (2- (4 ′, 6′-difluorophenyl) pyridinate N, C2 ') (2,4-pentanesionate), platinum (II) (2- (4', 6'-difluorophenyl) pyridinate N, C2 ') (6-methyl-2,4-heptaneoneate- O, O), bis (2- (2′-benzo [4,5-a] thienyl) pyridinate-platium (II) (2- (4 ′, 6′-difluorophenyl) Pyridinate N, C3 '), such as phosphorescent material such as iridium (acetylacetonate).

Further, the light emitting layer may contain a material (organic light emitting material / dopant) responsible for the electroluminescence generation function and a material (host material) responsible for other functions. In this case, the host material performs carrier injection and carrier transport, and is excited by recombination. The host material in an excited state moves excitation energy to the dopant. The dopant generates light when returning to the ground state. In addition, a mechanism in which the host material transports carriers to the dopant, performs recombination within the dopant, and generates light when the dopant returns to the ground state can be employed.
In general, a fluorescent material or a phosphorescent material is used as the dopant.

  The host material only needs to have the above functions, and a known material can be used. For example, distyrylarylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, quinolinolate metal complexes, triarylamine derivatives, azomethine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, silole derivatives, naphthalene derivatives, anthracene derivatives, di Examples thereof include carbazole derivatives, perylene derivatives, oligothiophene derivatives, coumarin derivatives, pyrene derivatives, tetraphenylbutadiene derivatives, benzopyran derivatives, europium complexes, rubrene derivatives, quinacridone derivatives, triazole derivatives, benzoxazole derivatives, and benzothiazole derivatives.

  The fluorescent material is a fluorescent material (fluorescent dye, fluorescent dopant), and emits light from the singlet excited state at room temperature, which emits light when transitioning to the ground state by obtaining energy from the host material. Material. In addition, a material that emits light when returning to the ground state by recombining carriers transported from the host material at room temperature can be employed. In general, a material having high fluorescence quantum efficiency is selected, and the addition amount is 0.01 wt% or more and 20 wt% or less with respect to the host material.

  The fluorescent material may be appropriately selected from known materials having the above properties, for example, europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, porphyrin derivatives, coumarin derivatives, europium complexes, rubrene derivatives, Nile Red 2- (1,1-dimethylethyl) -6- (2- (2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H-benzo (ij) quinolidine-9 -Yl) ethenyl) -4H-pyran-4H-ylidene) propanedinitrile (DCJTB), DCM, coumarin derivatives, quinacridone derivatives, distyrylamine derivatives, pyrene derivatives, perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives , Benzimidazole derivatives, chrysanthemum Derivatives, phenanthrene derivatives, distyryl benzene derivatives, tetraphenyl butadiene derivatives, rubrene derivatives, and the like.

  As a coumarin derivative, what is represented by the following general formula 1 can be mentioned, for example.

In General Formula 1, R ^{1 to} R ⁵ each independently represent a hydrogen atom or a hydrocarbon group, and the hydrocarbon group may have one or more substituents. The hydrocarbon group for R ^{1 to} R ⁵ is usually an aliphatic hydrocarbon group, preferably, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, an isopropenyl group, a 1-propenyl group, or a 2-propenyl group. , Butyl group, isobutyl group, sec-butyl group, tert-butyl group, 2-butenyl group, 1,3-butadienyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-pentenyl group, etc. Short chain long aliphatic hydrocarbon groups up to several 5, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclohexenyl group and other alicyclic hydrocarbon groups, phenyl group, o-tolyl group, m-tolyl group , P-tolyl group, xylyl group, mesityl group, o-cumenyl group, m-cumenyl group, p-cumenyl group, biphenylyl Aromatic hydrocarbon group such as, more, a hydrocarbon group by combinations thereof. One or more of the hydrogen atoms in the hydrocarbon group are, for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group , Ether groups such as isopentyloxy group, phenoxy group, benzyloxy group, acetoxy group, benzoyloxy group, ester group such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, fluoro group, chloro group, bromo group, iodo It may be substituted with a halogen group such as a group, and further a substituent by a combination thereof. Although it depends on the use of the organic EL device, preferred is a coumarin derivative in which all of R ^{2 to} R ⁵ are aliphatic hydrocarbon groups, and in particular, a coumarin derivative in which R ^{2 to} R ⁵ are all methyl groups, It is particularly excellent in physical properties and economy.

R ^{6 to} R ¹³ in the general formula 1 each independently represent a hydrogen atom or a substituent. Examples of the substituent in R ^{6 to} R ¹³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, an isopropenyl group, a 1-propenyl group, a 2-propenyl group, a butyl group, an isobutyl group, a sec-butyl group, tert-butyl group, 2-butenyl group, 1,3-butadienyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, 2-pentenyl group, hexyl group , An isohexyl group, a 5-methylhexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an octadecyl group and the like, an aliphatic hydrocarbon group having up to 20 carbon atoms, a cyclopropyl group, a cyclobutyl group, Such as cyclopentyl, cyclohexyl, cyclohexenyl, cycloheptyl, etc. Cyclic hydrocarbon group, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, xylyl group, mesityl group, o-cumenyl group, m-cumenyl group, p-cumenyl group, benzyl group, phenethyl group , Aromatic hydrocarbon group such as biphenylyl group, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, phenoxy group, benzyloxy group Ether groups such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, acetoxy group, benzoyloxy group and other ester groups, fluoro group, chloro group, bromo group, iodo group and other halogen groups, hydroxy group, carboxy group, Substituents by cyano groups, nitro groups, and combinations thereof are listed. I can get lost.

  More specifically, those represented by the following chemical formulas 1 to 23 can be mentioned. Like these compounds, the group of coumarin derivatives represented by the above general formula 1 has a high melting point and glass transition point, and as a result, the thermal stability is high.

The phosphorescent material is a phosphorescent material (phosphorescent pigment, phosphorescent dopant), and emits light from the singlet and triplet excited states at room temperature, which emits light when transitioning to the ground state by obtaining energy from the host material. It is a material that can be used. As the phosphorescent material, a material that can recombine carriers transported from the host material to be in an excited state and extract light from a singlet and a triplet when returning to a ground state can be used.
The addition amount (dope amount) of the phosphorescent material is generally 0.01% by weight or more and 30% by weight or less with respect to the host material.

The phosphorescent material is not particularly limited as long as it is a material that can utilize light emission from a singlet state and a triplet state in an excited state at normal temperature. For example, a known material selected as a phosphorescent material for a light emitting layer, for example, Factoris ( 2-phenylpyridine) iridium, bis (2-phenylpyridinato-N, C2 ′) iridium (acetylacetonate), 6-di (fluorophenyl) -pyridinate-N, C2 ′) iridium (acetylacetonate), Iridium (III) bis [4,6-di (fluorophenyl) -pyridinate-N, C2 ′] picolinate, platinum (II) (2- (4 ′, 6′-difluorophenyl) pyridinate N, C2 ′) (2 , 4-pentanesionate), platinum (II) (2- (4 ′, 6′-difluorophenyl) pyridinate N, C2 ′) 6-methyl-2,4-heptaneconionate-O, O), bis (2- (2′-benzo [4,5-a] thienyl) pyridinate-platium (II) (2- (4 ′, 6 '-Difluorophenyl) pyridinate N, C3') iridium (acetylacetonate), etc. In general, phosphorescent heavy metal complexes are often used.
For example, tris (2-phenylpyridine) iridium can be used as the green phosphorescent material. As the red phosphorescent material, 2,3,7,8,12,13,17,18-octaethyl-21H23H-porphine platinum (II) can be used. Moreover, you may change the center metal of these materials into another metal or a nonmetal.

The light emitting layer may be provided on the hole injecting and transporting layer by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.
The film thickness is generally about 1 nm to 100 nm, preferably about 2 to 50 nm, although it depends on the material used.

  Note that the chromaticity, saturation, brightness, luminance, and the like of the light emitted from the light emitting layer can be adjusted by selecting the type of material forming the light emitting layer, adjusting the amount of addition, adjusting the film thickness, and the like.

  For example, the light emitting layer emitting blue (blue light emitting layer) used for the organic EL element 1B emitting blue is preferably formed by mixing a dopant whose emission color is blue and a host material, for example, by co-evaporation. it can.

  As the dopant whose emission color is blue, known dopants for blue light emission can be appropriately adopted. For example, distyrylamine derivatives, pyrene derivatives, perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, chrysene Derivatives, phenanthrene derivatives, distyrylbenzene derivatives, tetraphenylbutadiene and the like can be mentioned.

  As the host material for the blue light-emitting layer, a known host material used in the light-emitting layer of the organic EL element having a blue emission color can be appropriately employed. For example, a distyrylarylene derivative, a stilbene derivative, a carbazole derivative, a triaryl Examples thereof include amine derivatives, anthracene derivatives, pyrene derivatives, coronene derivatives, bis (2-methyl-8-quinolinolato) (p-phenylphenolato) aluminum (BAlq), and the like.

  Examples of the dopant having a red emission color used in the organic EL element 1R that emits red include, for example, europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, porphyrin derivatives, Nile red, 2- (1,1-dimethyl). Ethyl) -6- (2- (2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H-benzo (ij) quinolizin-9-yl) ethenyl) -4H-pyran -4H-ylidene) propanedinitrile (DCJTB), DCM and the like.

  Examples of the dopant having a green emission color used in the organic EL element 1G that emits green include a coumarin derivative and a quinacridone derivative.

  As a host material used for a red light emitting layer or a green light emitting layer, a known host material used in a light emitting layer of an organic EL element having a light emission color of red or green can be appropriately employed. Benzene derivatives, distyrylamine derivatives, quinolinolate metal complexes, triarylamine derivatives, oxadiazole derivatives, silole derivatives, dicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, etc. Alq3, a tetramer of triphenylamine, and 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi) are particularly preferably used.

  There are the following methods for adjusting the emission color of the light emitting layer. The emission color may be adjusted using one or more of these methods.

A method of adjusting the emission color by adding a material that promotes or inhibits emission.
For example, a so-called assist dopant that receives energy from the host material and transfers this energy to the dopant can be added to facilitate energy transfer from the host material to the dopant. As an assist dopant, it selects from a well-known material suitably, for example, may be selected from the above-mentioned host material and the material which can be utilized as a dopant.

A method of adjusting the emission color by adding a wavelength converting material to a layer (including the substrate 2) on the light extraction side of the light emitting layer.
As this material, a known wavelength conversion material can be used. For example, a fluorescence conversion substance that converts light emitted from the light emitting layer into other light having a low energy wavelength can be used. The type of the fluorescence conversion substance is appropriately selected according to the wavelength of light to be emitted from the target organic EL device and the wavelength of light emitted from the light emitting layer. The amount of the fluorescent conversion substance used can be appropriately selected according to the type within a range that does not cause concentration quenching, but is 10 ⁻⁵ to 10 ⁻⁴ mol / percent of the transparent resin (uncured). A liter is appropriate. Only one type of fluorescent conversion substance may be used, or a plurality of types may be used in combination. When a plurality of types are used in combination, white light or intermediate color light can be emitted in addition to blue light, green light, and red light. Specific examples of the fluorescence conversion substance include the following substances (a) to (c).

(A) What emits blue light when excited by ultraviolet light, Stilbene dyes such as 1,4-bis (2-methylstyrin) benzene, trans-4,4'-diphenylstilbene, 7-hydroxy-4-methylcoumarin Coumarin dyes such as 4,4'-bis (2,2-diphenylvinyl) biphenyl and other aromatic dimethylidin dyes.

(B) one that emits green light when excited by blue light 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin (coumarin 153 ) And other coumarin dyes.

(C) Excited by light having a wavelength from blue to green and emitting light having a wavelength from orange to red 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyrylyl) -4H -Pyran, 4- (dicyanomethylene) -2-phenyl-6- (2- (9-eurolidyl) ethenyl) -4H-pyran, 4- (dicyanomethylene) -2,6-di (2- (9-eurolidyl) ) Ethenyl) -4H-pyran, 4- (dicyanomethylene) -2-methyl-6- (2- (9-eurolidyl) ethenyl) -4H-pyran, 4- (dicyanomethylene) -2-methyl-6- ( Cyanine dyes such as 2- (9-eurolidyl) ethenyl) -4H-thiopyran, 1-ethyl-2- (4- (p-dimethylaminophenyl) -1,3-butadienyl) -pyridium- Pyridine dyes such as percollate (pyridine 1), xanthine dyes such as rhodamine B and rhodamine 6G, and oxazine dyes.

[Electron injection transport layer]
An electron injection transport layer is a layer provided between a cathode and a light emitting layer, and is a layer which transports the electron inject | poured from the cathode to a light emitting layer, and provides the following properties to an organic EL element.
・ Drive voltage is lowered.
・ Since electron injection from the cathode to the light emitting layer is stabilized, the service life is extended.
-Since the adhesion between the cathode and the light emitting layer is increased, the uniformity of the light emitting surface can be increased.
-Covers the protrusions of the cathode and reduces device defects.

As a material for forming an electron injection / transport layer, a known material that can be used as an electron injection material of a photoconductive material, or an arbitrary material among known materials used for an electron injection / transport layer of an organic EL device In general, a material whose electron affinity is between the work function of the cathode and the electron affinity of the light emitting layer is used.
Specifically, 1,3-bis [5 ′-(p-tert-butylphenyl) -1,3,4-oxadiazol-2′-yl] benzene or 2- (4-bifinylyl) -5- Oxadiazole derivatives such as (4-t-butylphenyl) -1,3,4-oxadiazole; 3- (4′-tert-butylphenyl) -4-phenyl-5- (4 ″ -biphenyl) Triazine derivatives such as -1,2,4-triazole, etc. Triazine derivatives, perylene derivatives, quinoline derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorenone derivatives, thiopyrandioxide derivatives, anthraquinodis Heterocyclic tetracarboxylic anhydrides such as methane derivatives, thiopyran dioxide derivatives, naphthalene perylene, carbodiimi It can be used fluorenylidene methane derivatives, anthraquinodimethane derivatives, anthrone derivatives, distyryl pyrazine derivatives, silole derivatives, phenanthroline derivatives, also imidazopyridine derivatives.

  Organometallic complexes such as bis (10-benzo [h] quinolinolato) beryllium, beryllium salt of 5-hydroxyflavone, and aluminum salt of 5-hydroxyflavone are also preferably selected, but 8-hydroxyquinoline or its derivatives A metal complex is also particularly suitably selected. Specific examples include metal chelate oxinoid compounds containing chelates of oxine (generally 8-quinolinol or 8-hydroxyquinoline) such as tris (8-quinolinol) aluminum and tris (5,7-dichloro-8-quinolinol). Examples thereof include aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, and tris (2-methyl-8-quinolinol) aluminum. Moreover, the metal complex etc. which the center metal of these metal complexes replaced with indium, magnesium, copper, calcium, tin, zinc, or lead are mentioned. Metal-free or metal phthalocyanine or those having a terminal substituted with an alkyl group or a sulfone group is also preferably used.

  The electron injecting and transporting layer may be formed of only one kind of material as described above, or may be formed by mixing a plurality. Moreover, the multilayer structure which consists of several layers of the same composition or a different composition may be sufficient.

The electron injecting and transporting layer is formed by a known thin film forming method such as a sputtering method, an ion plating method, a vacuum vapor deposition method, a spin coating method, or an electron beam vapor deposition method using the above-described materials.
The film thickness varies depending on the material used, but is usually 5 nm to 5 μm.

  In addition, when an electron injection transport layer is provided in the light extraction side rather than a light emitting layer, it needs to be transparent with respect to the light to extract. Therefore, a material that is transparent to the light when it is thinned is appropriately selected from the materials that can form the electron injecting and transporting layer as described above, and generally the transmittance for the extracted light is more than 10%. Set to be larger.

[Other layers, additives]
The organic EL element according to the present embodiment may be provided with a known layer other than the above-described layers, or a known additive (dopant) or the like may be added (doping) to the constituent layers. Good.

For example, when providing the layers shown in the above-described layer configuration examples such as an electron transport layer, a hole transport layer, a hole injection layer, etc., pay attention to the functions (carrier transport function, carrier injection function) assigned to these layers. Then, an appropriate material may be selected from the materials as described above and manufactured in the same manner as each layer described above.
Further, for example, it can be modified as follows.

[Layers provided between the above layers]
You may provide the layer for improving the adhesiveness of layers, or improving electron injection property or hole injection property.
For example, a cathode interface layer (mixed electrode) in which a material for forming a cathode and a material for forming an electron injecting and transporting layer are co-evaporated may be provided between the two. Thereby, the energy barrier of the electron injection which exists between a light emitting layer and a cathode can be eased. In addition, the adhesion between the cathode and the electron injecting and transporting layer can be improved.
The material for forming the cathode interface layer can be used without particular limitation as long as it is a material that imparts the above performance to the cathode interface layer, and known materials can also be used. For example, use of alkali metal such as lithium fluoride, lithium oxide, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, fluoride of alkaline earth metal, oxide, chloride, sulfide, etc. it can. The cathode interface layer may be formed of a single material or a plurality of materials.
The film thickness is about 0.1 nm to 10 nm, preferably 0.3 nm to 3 nm.
The cathode interface layer may be formed uniformly in the cathode interface layer, may be formed non-uniformly, may be formed in an island shape, or a known thin film forming method such as a vacuum evaporation method. Can be formed.

  A layer (block layer) that prevents the movement of holes, electrons, excitons, and the like may be provided in at least one of the layers described above. For example, a hole blocking layer may be provided adjacent to the cathode side of the light emitting layer in order to prevent holes from passing through the light emitting layer and to efficiently recombine with electrons in the light emitting layer. Examples of the material for forming the hole block layer include known materials such as triazole derivatives, oxadiazole derivatives, BAlq, and phenanthroline derivatives, but are not particularly limited thereto.

  A layer (buffer layer) that relaxes a hole or electron injection barrier may be provided in at least one of the above-described layers. For example, a buffer layer may be inserted between the anode and the hole injecting and transporting layer transporting layer, or between the organic layers stacked adjacent to the anode for the purpose of relaxing the injection barrier against hole injection. As a material for forming the buffer layer, a known material such as copper phthalocyanine is used, but is not particularly limited thereto.

[Protective member]
For the purpose of preventing the organic EL element from coming into contact with oxygen or moisture, a protective member (sealing layer, passivation film) may be provided on the side opposite to the substrate.
Examples of the material used for the protective member include organic polymer materials, inorganic materials, and photocurable resins. The material used for the protective member may be used alone or in combination. You may use together. The protective member may have a single layer structure or a multilayer structure. Moreover, you may provide another function to a protection member. For example, there is a function of protecting the organic layer 11 from external influences (temperature change, pressure, etc.).

Examples of organic polymer materials include fluorinated resins such as chlorotrifluoroethylene polymer, dichlorodifluoroethylene polymer, a copolymer of chlorotrifluoroethylene polymer and dichlorodifluoroethylene polymer, polymethyl methacrylate, poly Acrylic resins such as acrylate, epoxy resins, silicone resins, epoxy silicone resins, polystyrene resins, polyester resins, polycarbonate resins, polyamide resins, polyimide resins, polyamideimide resins, polyparaxylene resins, polyethylene resins, polyphenylene oxide resins, etc. be able to.
Examples of the inorganic material include polysilazane, diamond thin film, amorphous silica, electrically insulating glass, metal oxide, metal nitride, metal carbonide, metal sulfide and the like.

In addition, you may add an above described fluorescence conversion substance to the above materials.
In addition, the organic EL element can be protected by being enclosed in an inert substance such as paraffin, liquid paraffin, silicone oil, fluorocarbon oil, or zeolite-added fluorocarbon oil.

  Naturally, it may be protected by can sealing. Specifically, the organic layer may be sealed with a sealing member such as a sealing plate or a sealing container for the purpose of blocking moisture and oxygen from the outside. Even if it installs a sealing member only in the electrode side of a back side, you may cover the whole organic EL element with a sealing member. The shape, size, thickness and the like of the sealing member are not particularly limited as long as the organic layer can be sealed and external air can be blocked. As a material used for the sealing member, glass, stainless steel, metal (aluminum, etc.), plastic (polychlorotrifluoroethylene, polyester, polycarbonate, etc.), ceramic, or the like can be used.

  When installing the sealing member on the organic EL element, a sealing agent (adhesive) may be used as appropriate. When covering the whole organic EL element with a sealing member, you may heat-seal sealing members without using a sealing agent. As the sealant, an ultraviolet curable resin, a thermosetting resin, a two-component curable resin, or the like can be used.

  Further, a water absorbent or an inert liquid may be inserted into the space between the sealing container and the organic EL element. The moisture absorbent is not particularly limited, and specific examples include barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride, cesium fluoride. , Niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide and the like. As the inert liquid, paraffins, liquid paraffins, fluorinated solvents (perfluoroalkane, perfluoroamine, perfluoroether, etc.), chlorinated solvents, silicone oils, and the like can be used.

[Doping to hole injection transport layer and electron injection transport layer]
The hole injecting and transporting layer and the electron injecting and transporting layer may be doped with an organic light emitting material (dopant) such as a fluorescent material or a phosphorescent material, and these layers may emit light.

<Doping of alkali metal or alkali metal compound to the layer adjacent to the cathode>
When a metal such as aluminum is used for the cathode, an alkali metal or an alkali metal compound may be doped into a layer adjacent to the cathode in order to reduce the energy barrier between the cathode and the organic light emitting layer 31. Since the organic layer is reduced by the added metal or metal compound to generate anions, the electron injecting property is increased and the applied voltage is decreased. Examples of the alkali metal compound include oxides, fluorides, and lithium chelates.

(electrode)
One of the transparent electrode 10 and the back electrode 12 functions as an anode, and the other functions as a cathode. In the present embodiment, any electrode may be an anode (a cathode). First, the anode will be described.

The anode is an electrode that injects holes into the organic layer 11.
The material for forming the anode may be any material that imparts the above-described properties to the anode. Generally, a known material such as a metal, an alloy, an electrically conductive compound, or a mixture thereof is selected and contacted with the anode ( The work function of the (surface) is 4 eV or more.

Examples of the material for forming the anode include the following.
Metal oxides and metal nitrides such as ITO (indium-tin-oxide), IZO (indium-zinc-oxide), tin oxide, zinc oxide, zinc aluminum oxide, titanium nitride;
Metals such as gold, platinum, silver, copper, aluminum, nickel, cobalt, lead, chromium, molybdenum, tungsten, tantalum, niobium;
These metal alloys and copper iodide alloys,
Conductive polymers such as polyaniline, polythiophene, polypyrrole, polyphenylene vinylene, poly (3-methylthiophene), and polyphenylene sulfide.

  When the transparent electrode 10 is used as an anode, in general, the transmittance for extracted light is set to be larger than 10%. When extracting light in the visible light region, ITO having high transmittance in the visible light region is preferably used.

When the back electrode 12 is used as an anode, it is preferably configured as a reflective electrode. In this case, among the above materials, a material having the ability to reflect the light extracted to the outside is appropriately selected, and in general, a metal, an alloy, or a metal compound is selected.
Further, the back electrode 12 may be provided with absorption performance in order to prevent contrast and the like and to prevent reflection of external light. In order to give the back electrode 12 the absorption performance, a material that exhibits the absorption performance when the electrode is formed may be appropriately selected from the materials described above.

  The anode may be formed of only one kind of material as described above, or may be formed by mixing a plurality of materials. Moreover, the multilayer structure which consists of several layers of the same composition or a different composition may be sufficient.

  Although the film thickness of the anode depends on the material used, it is generally in the range of about 5 nm to 1 μm, preferably about 10 nm to 1 μm, more preferably about 10 nm to 500 nm, particularly preferably about 10 nm to 300 nm, desirably 10 nm to 200 nm. Selected.

The anode is formed by a known thin film forming method such as a sputtering method, an ion plating method, a vacuum vapor deposition method, a spin coat method, or an electron beam vapor deposition method using the above-described materials.
The sheet electrical resistance of the anode is preferably set to several hundred Ω / □ or less, more preferably about 5 to 50 Ω / □.

Further, the surface of the anode may be subjected to UV ozone cleaning or plasma cleaning.
In order to suppress the occurrence of short circuits and defects in the organic EL element, the surface roughness may be controlled to 20 nm or less as a mean square value by a method of reducing the particle size or a method of polishing after film formation.

The cathode is an electrode that injects electrons into the organic layer 11 (in the above-described layer configuration, an electron injection transport layer).
As a material for forming the cathode, a metal, an alloy, an electrically conductive compound having a work function of, for example, less than 4.5 eV, generally 4.0 eV or less, typically 3.7 eV or less in order to increase electron injection efficiency, and A mixture of these is employed.

  Examples of the electrode material as described above include lithium, sodium, magnesium, gold, silver, copper, aluminum, indium, calcium, tin, ruthenium, titanium, manganese, chromium, yttrium, aluminum-calcium alloy, and aluminum-lithium alloy. , Aluminum-magnesium alloys, magnesium-silver alloys, magnesium-indium alloys, lithium-indium alloys, sodium-potassium alloys, magnesium / copper mixtures, aluminum / aluminum oxide mixtures, and the like. Moreover, the material employable as a material used for an anode can also be used.

  When the back electrode 12 is a cathode, a material having the ability to reflect the light extracted to the outside is preferably selected from the above materials, and generally a metal, an alloy, or a metal compound is selected. .

  When the transparent electrode 10 is a cathode, it is generally set so that the transmittance for extracted light is greater than 10%. For example, a transparent conductive oxide is laminated on an ultra-thin magnesium-silver alloy. An electrode formed by the above method is employed. In this cathode, a buffer layer to which copper phthalocyanine or the like is added is preferably provided between the cathode and the organic layer 11 in order to prevent the light emitting layer from being damaged by plasma when the conductive oxide is sputtered.

  The cathode may be formed of the above materials alone or a plurality of materials. For example, if 5% to 10% of silver or copper is added to magnesium, the oxidation of the cathode can be prevented, and the adhesion of the cathode to the organic layer 11 can be improved.

The cathode may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.
For example, the following structure may be used.
In order to prevent oxidation of the cathode, a protective layer made of a corrosion-resistant metal is provided on the portion of the cathode that does not contact the organic layer 11.
For example, silver or aluminum is preferably used as the material for forming the protective layer.

In order to reduce the work function of the cathode, an oxide, fluoride, metal compound or the like having a small work function is inserted into the interface portion between the cathode and the organic layer 11.
For example, a material in which the cathode material is aluminum and lithium fluoride or lithium oxide is inserted in the interface portion is also used.

The cathode can be formed by a known thin film deposition method such as a vacuum deposition method, a sputtering method, an ionization deposition method, an ion plating method, or an electron beam deposition method.
The sheet electrical resistance of the cathode is preferably set to several hundred Ω / □ or less.

-Auxiliary electrode It is naturally possible to provide an auxiliary electrode. The auxiliary electrode is provided so as to be electrically connected to the anode and / or the cathode, and is made of a material having a lower volume resistivity than the electrode to be connected. If the auxiliary electrode is formed of such a material, it becomes possible to reduce the volume resistivity of the entire electrode provided with the auxiliary electrode, and the maximum difference in the magnitude of the current flowing to each point constituting the organic layer 11 is determined. The size can be reduced as compared with the case where no auxiliary electrode is provided.

Examples of the material for forming the auxiliary electrode include tungsten (W), aluminum (Al), copper (Cu), silver (Ag), molybdenum (Mo), tantalum (Ta), gold (Au), and chromium (Cr). , Titanium (Ti), neodymium (Nd), and alloys thereof.
Specific examples of these alloys include alloys such as Mo—W, Ta—W, Ta—Mo, Al—Ta, Al—Ti, Al—Nd, and Al—Zr. Further, as the material of the auxiliary wiring layer, which is a compound of metal and _{silicon, TiSi 2, ZrSi 2, HfSi} 2, VSi 2, NbSi 2, TaSi 2, CrSi 2, WSi 2, CoSi 2, NiSi 2, PtSi Pd ₂ Si and the like are also preferable. Moreover, the structure which laminated | stacked these metals and * silicon compounds, respectively may be sufficient.

The auxiliary electrode may be a single-layer film made of the above materials, but it is also preferable to use two or more types of multilayer films in order to improve the stability of the film. Such a multilayer film can be formed using the above metals or their alloys. For example, in the case of three layers, Ta layer and Cu layer and Ta layer, and Ta layer and Al layer and Ta layer, in the case of two layers, Al layer and Ta layer, Cr layer and Au layer, Cr layer and Al layer, and A combination of an Al layer and a Mo layer can be given.
Here, the stability of the film refers to a property that can maintain a low volume resistivity and is not easily corroded by a liquid or the like used for the treatment during etching. For example, when the auxiliary electrode is made of Cu or Ag, the auxiliary electrode may have a low volume resistivity but may be easily corroded. On the other hand, the stability of the auxiliary electrode is enhanced by laminating a metal with excellent corrosion resistance, such as Ta, Cr, Mo, etc., on the upper and / or lower part of the metal film made of Cu or Ag. be able to.

In general, the thickness of the auxiliary electrode is preferably set to a value within the range of 100 nm to several tens of μm, and more preferably set to a value within the range of 200 nm to 5 μm.
The reason for this is that when the film thickness is less than 100 nm, the resistance value is increased, which is not preferable as the auxiliary electrode. On the other hand, when the film thickness exceeds several tens of μm, it becomes difficult to flatten and the organic EL element 4 may be defective. Because there is.

For example, the width of the auxiliary electrode is preferably a value within a range of 2 μm to 1,000 μm, and more preferably a value within a range of 5 μm to 300 μm.
The reason is that if the width is less than 2 μm, the resistance of the auxiliary electrode may be increased. On the other hand, if the width exceeds 100 μm, extraction of light to the outside may be hindered. .

<Substrate 3>
The substrate 3 is a mainly plate-like member that supports the organic EL element 1. The organic EL element 1 is generally manufactured as an organic EL device supported by the substrate 3 because the constituent layers are very thin.
In this example, since the bottom emission type organic EL element 1 is used, the substrate 3 emits light that is emitted to the outside, that is, R light (wavelength ( wavelength that is incident / exited on the two-dimensional photonic crystal layer 2R)). Band ) light), G light and B light.

  Since the substrate 3 is a member on which the organic EL element 1 is laminated, it is preferable that the light incident surface 31 has planar smoothness. Further, when the two-dimensional photonic crystal layer 2 is directly provided on the light emitting surface 32, it is preferable that the light emitting surface 32 also has planar smoothness.

  A known substrate can be used as the substrate 3 as long as it has the above-described performance. In general, a ceramic substrate such as a glass substrate, a silicon substrate, or a quartz substrate, or a plastic substrate is selected. Furthermore, a substrate made of a composite sheet in which a plurality of substrates of the same or different types are combined can be used.

  In addition, when using a top emission type organic EL element, the substrate does not need to be transparent. In this case, a metal substrate or a substrate in which a metal foil is formed on a support can be suitably used.

<Drive system>
As a display driving method, a known driving method such as an active matrix driving method or a passive matrix driving method may be adopted as appropriate. In other words, the pixel structure shown in FIG. 1 may be provided for each pixel, and each pixel (each subpixel) may be caused to emit / not emit light using the known display driving method as described above to display an image.

In addition, shutter means for adjusting the amount of light emitted to the outside of the display may be provided. For example, as shown in FIG. 4, a reflective or transflective liquid crystal display panel 6 having pixels (shutters) corresponding to the sub-pixels is provided on the light extraction side of the two-dimensional photonic crystal layer 2. Also good. Accordingly, each organic EL element 1 may be always lit, and gradation control may be performed by a known control method using the liquid crystal display panel 6. That is, when the light from the sub-pixel emitting red light is emitted to the outside, the sub-pixel 6R of the liquid crystal display panel 6 may be configured to transmit the incident light. The same applies to the other subpixels. In addition, about the subpixel which does not permeate | transmit light outside, you may make it not make the organic EL element 2 of the subpixel light.
In addition, when a transflective liquid crystal display panel is used, when the outside of the display is sufficiently bright, it is possible to perform display using external light without causing current to flow through the organic EL element 1 (no light is emitted). .

In the above-described embodiment, the description has been given of the mobile phone that constitutes the display by RGB sub-pixels. However, the display may be constituted by a combination of other organic EL elements that emit light with other known colors. In this case as well, a two-dimensional photonic crystal layer having periodicity corresponding to the emission color of each element may be provided on the light extraction side of each organic EL element.
In addition, each organic EL element only needs to emit at least the above-described color (for example, the organic EL element 1R has light of red wavelength), and it is natural that light of other wavelengths may be emitted. is there.
Next, a color display according to the second embodiment will be described with reference to FIG.

《Second color display》
The second color display is configured by forming one pixel by a plurality of sub-pixels and arranging a plurality of pixels. As shown in FIG. 5, each subpixel includes (c) an organic EL element 1 </ b> W, and (d) a two-dimensional wavelength output from the subpixel provided on the light extraction side of the organic EL element 1 </ b> W. Photonic crystal layers 2R, 2G, and 2B are provided. Further, (e) the organic EL elements 1W, 1W ′, 1W ″ (hereinafter collectively referred to as “1W”) of each subpixel are elements that emit light having a wavelength emitted from all the subpixels. Is done.

With this configuration, the same effect as that of the first color display can be obtained. In addition, since the organic EL elements of the subpixels only need to emit the same color, the organic EL elements 1W of the subpixels can be formed simultaneously.
Since the configuration other than the organic EL element 1W is the same as that of the first color display, the organic EL element 1W will be described in detail below.

  The organic EL element 1W is formed by laminating the light emitting layer of the organic EL element 1 in the first color display, and each layer emits light having a wavelength (peak wavelength) different from at least the other layer. Or may be configured. In this example, a configuration in which R, G, and B light is emitted from the organic EL element 1W may be employed.

  The light emitting layer that emits a plurality of colors can be produced by adding a dopant for each color as described above or emitting a plurality of colors such that the dopant and the host emit different colors. As a method for manufacturing such a light emitting layer, the material constituting the layer is formed by mixing by co-evaporation or the like, or the constituent material is dissolved or dispersed in a binder resin or the like, and this solution or dispersion is applied. Or can be formed.

In addition, by adding a plurality of dopants in the same layer, the emission color is mixed, or two or more lights are emitted, or after energy transfer from the host material to the low energy first dopant, It is also possible to efficiently transfer energy to the dopant.
When the host material adopts a mechanism that transports carriers to the dopant and causes recombination in the carriers, it is possible to improve the efficiency of carrier movement.

  It should be noted that the color display according to the above embodiment can be changed as appropriate within the scope of the present invention. For example, it is not necessary to provide the two-dimensional photonic crystal layer 1 for a subpixel that can emit a sufficient amount of light required for a display using only the organic EL element 1.

  In the above example, a display that displays white in red, green, and blue has been described. However, a complementary color relationship such as a blue / yellow combination, a light blue / orange combination, or a green / purple combination is emitted. You may express white. Of course, colors other than white may be expressed.

Each of the organic EL elements 1W may have substantially the same layer configuration, or the corresponding layers may have approximately the same configuration, but it is needless to say that the organic EL elements 1W need not be configured in this way.
However, if each organic EL element 1W has substantially the same layer configuration, or corresponding layers have substantially the same structure, it is possible to simultaneously perform one or a plurality of steps of manufacturing each organic EL element 1W. Compared with the case where a different configuration or the like is adopted for each element, it is possible to reduce the number of steps for manufacturing a color display or to simplify the steps.

It is principal part sectional drawing for demonstrating the cross-sectional structure of 1 pixel of the 1st color display which concerns on this Embodiment. It is a schematic diagram for demonstrating the structure of the photonic crystal layer 2 which concerns on this Embodiment. It is principal part sectional drawing for demonstrating the one aspect | mode of the organic EL element 1 in a 1st color display. It is sectional drawing for demonstrating the one aspect | mode of the drive method of a display. It is principal part sectional drawing for demonstrating the cross-sectional structure of 1 pixel of the 2nd color display which concerns on this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Organic EL element 1R: Organic EL element which emits red light 1G: Organic EL element which emits green light 1B: Organic EL element which emits blue light 1W: Organic EL element which emits white light 2: Two-dimensional photonic crystal Layer 2R: Two-dimensional photonic crystal layer that transmits light in the red wavelength / wavelength band 2G: Two-dimensional photonic crystal layer that transmits light in the green wavelength / wavelength band 2B: Light in the blue wavelength / wavelength band Transmitting two-dimensional photonic crystal layer 3: Substrate (transparent substrate)
31: Light incident surface 32: Light exit surface 4: Transmission type or transflective liquid crystal display device

Claims (4)

A color display in which one pixel is constituted by a plurality of sub-pixels and a plurality of pixels are arranged,
Each subpixel is
An electroluminescent element that emits at least light having a wavelength emitted by the subpixel;
A two-dimensional photonic crystal layer for a wavelength emitted from a subpixel, provided on the light extraction side of the electroluminescent element;
Color display using electroluminescent elements. A color display in which one pixel is constituted by a plurality of sub-pixels and a plurality of pixels are arranged,
Each subpixel is
An electroluminescent element;
A two-dimensional photonic crystal layer for a wavelength emitted from the subpixel, provided on the light extraction side from the electroluminescent element;
The electroluminescent element of each subpixel is an element that emits light having a wavelength emitted by all the subpixels.
Color display using electroluminescent elements A color display using the electroluminescent element according to claim 1 or 2,
A color display using electroluminescent elements, wherein the electroluminescent elements in each subpixel have substantially the same layer structure. A color display using the electroluminescent element according to any one of claims 1 to 3,
The color display using an electroluminescent element, wherein the electroluminescent element is an organic electroluminescent element.

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